Radius belts are used in various applications for material handling as well as for food processing. For processes with long dwell times, spiral conveyors are commonly used. It has been known to use modular belts constructed of steel for these applications. However, the wear on the belts may produce blackening of the steel which contaminates the foodstuff. Also, belts made of steel are typically heavy, expensive and costly to repair. In response to some of these issues, it has been known to use plastic belt modules with steel pivot rods. These belts address some of the drawbacks but still suffer from the blackening problems. Also, steel rods concentrate pulling forces in a radius belt at one single link, whereas plastic rods are usually flexible enough to distribute the load onto two or more of the outermost links of the belt. Accordingly, it is preferable to form a belt from all plastic components.
Belts made entirely of plastic solve most of the above-described problems, but have the shortcoming of lower stiffness (lower modulus of elasticity) and therefore do not allow large distances between wear strips. Also, the reduced stiffness of plastic belts may create some problems for radius belts. For example, when a radius belt rounds a curve, radial compression forces act on the module rows. These forces may cause compression of the plastic belts in this area. In addition, the bending stiffness of plastic belts is reduced. This reduced stiffness negatively affects the bending stiffness of the complete belt, if it is resting on support strips with large distances as common for spiral machines. Accordingly, there is a need for radius belts made entirely of plastic materials that offer an improved stiffness without affecting the ability of the belt to collapse in a curve. It is also desirable to have the stiffness as equal as possible over the full belt width. These belts have particular application for spiral conveyors and other very large radius applications.